Railway signaling apparatus



L. O. GRONDAHL RAILWAY SIGNALING AP ARATUS Dec. 27, 1927.

2 Sfieets-Sheet 1 Original Filed Jan. '24. 1924 INVENTOR 2 Dec. 27,1927.

I O. GRONDAHL.

RAILWAY SIGNALING APPARATUS Original Filed Jan. 24,1924 2 Sheets-Sheep 2IN VENTOR aux-M Patented Dec. 27, 1927.

more!) STATES tenses PATENT OFFiCE.

LAES'D. 'GEONDAI-ZL, OF EITTSB-URGH,"EENNSYLVKNIA, LASSIGNOR TO THEUNION 72 E it NEvYLVANIA.

Continuation of application Seine-1N0.

f y invention relates to railway signaling al paratus, and particularlyto apparatus of the type comprising roadside signals c011 trclled'hytrack 'circuitswhich are responsive to the presence of trains on thetrack. I

The presentapplication is a continuation of my copending application,Serial No. 688,201, filed January 2t, 1924, for railway signalingapparatus, in so far as the "subjectmatter common to the twoisconcerned.

will describe two forms of signalin t apparatus embodying my invention,and will then point out the novel 'tea'tures t-hereot in claims. I l

in the accompanying drawings, Figs. 1 and 2am diagrammatic views showingtwo terms ot railway signaling apparatus 'embodying my invention.

lftet'erring first to Fig. 1, the reference ch21 acters 1 and 1designate the track rails of a stretch of railway track over whichtra'liic normally moves in the direction indicated by the arrow. Thesetrack rails are diviced, by means of insulated joints 2, into a.plurality ofsuccessive-track sections A"B, ll- 0. etc. i I j Each trackscection is provided with a suitable traclzway signal. As here showneach signal comprises three indicators such as'signal la as, designatedby the reference characte I and it with exponents 'corresponoi to thelocation and arranged when energized to indicate proceecl, cautiou, andstop, respectively.

Each track section also provided with five thermo-sensitive relaysdesignated by the reference characters H, F, J, K, and L, with exponentscorresponding to the locations. Each such thermo-sensitive relaycoinprises a heater 8 and an element 9 of thermo-sensitive material,that is, material which has the characteristic of varyingfi-ts elecric'al resistance in response to variations the temperature of theelement. Each therinc-sensitive element 9 is electrically insu- "-atedfrom the associated heater '8 but is subjected to variations in thetemperature'of such heater. The parts are so proportioned that theresistance of each thermo-sensitive element 9 is comparatively high whenthe associated heater is die-energized butthat who the associated heateris energized, the recipe. ture of the thermo-sensitive element 'TCH 8cSIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPQRATION RA-IIELW'A'YSIGNALING APPARATUS.

688,207, filed January 24, 1824. This application filed May 18, 1926.Serial No. 109,869.

is increased and the resistance of theelemeat reduced to a-comparativ'ely low value. v I

Referring particularly to the apparatus located at point A, theright-hand terminal of the heater 8 of thermo-sensitive relay J and theleftdi'andterminal of heater 8 of 'thermo-sen-sitive relay K areconnected togetheijat common terminal cl. This common terminal d isconnected, through heater 8 of relay Lflwith rail 1 of the section tothe left of point A. The left-hand terminal of heater 8 of relay J5 iscorrected with will of this section through the medium of a deice 1-which'permits current to flow through the heater of relay J in only onedirection. This device. comprises a unidirectional current carryingdevice or asymmetrical unit of any desired form and may conveniently bea copper oxide asymmetrical unit such as described in an application forUnited States Letters Patent, Serial N 1,111, filed January 7, 1925, byLars O. Grondahl for unidirectional current carrying devices. Theright-hand terminal of heater 8 of relay K is connected with rail 1through an asymmetrical unit 5. :It should be noticed that unit isoppositely disposed with respect to unit 4, that is, these two unitsconduct most readily in opposite directions and hence, when rail 1 ispositive with respect to rail 1", current flows throughthe heaters ofrelays J and L whereas, when rail 1 is positive with respect to rail 1,current flows through the heaters of relays K and L Energy is suppliedto the apparatus at each location from a line transformer designated bythe reference character TV with a suitable exponent and having a primarywinding 10 constantly supplied with alternating currentfrom somesuitable source such as an alternator D, over line wires 3 and 3. 1

'VVhen relay J is energized, lamp G is energized, current passing fromsecondary 13 ot transformer T through wire 16, heater 8 of relay H wire17, 't-hermosensitive element 9 of relay J wire 18, lamp G and wires 19and 20 back to secondary 13 of transformer-T "Under this condition aproceed indication is displayed at location A. When relay '1 is"energized, lamp Y is lighted to display a caution indication, currentthen flowing from secondary 13 of transformer T through wire 16, heater8 of relay H wire 17, thermo-sensitive element9 of relay K, wire 21,lamp Y and wires 19 and'2O back to secondary 13. of transformer T Itwill be noticed that when either indicator Gr or Y is energized, relay His also energized.

Lamp R is provided with a circuit which passes from secondary 12 oftransformer T through wires 22 and 23, resistance 24, wire 25, lamp Rwire 26, heater 8 of relay F and wire 27 back to secondary 12 of transformer T This circuit is so adjusted and proportioned that lamp R isnormally enen gized. When relay H is energized, however, current flowsfrom secondary 11 of transformer T through wire 23, resistance 24, wire28, thermo-sensitive element 9 of relay H and wire 29 back to secondary11 of transformer T The parts are so arranged and proportioned that thevoltage drop in resistance 24 due to current flowing over this circuitis equal in magnitude and opposite in direction to the electromotiveforce applied to lamp R by secondary 12. It follows that when relay H isenergized, the electromotii-e force applied to lamp R is neutralized bythe voltage drop in resistance 24 and lampR is therefore de-energized.But I have already explained that relay H is energized when either lampsG or Y is energized, and it is therefore obvious that when either lamp Gor Y is lighted, lamp R isextinguished. I

Relays L and F control the supply of track circuit current to section ABin the following manner. The right-hand terminalof winding 14: oftransformer T and the left-hand terminal of winding 15 of thistransformer are connected, by wire 32, with rail l of section A-B. Theleft-hand terminal of winding 1% is connected with rail 1 of section AB,through wire 30, thermosensitive' element 9 of relay L wire 31, and anasymmetrical unit (3, to rail 1. The righthand terminal of winding 15 isconnected, through wire 33, thermo-sensitive element 9 of relay F wire34, and asymmetrical unit 7 to rail 1. Units 6 and 7 are similar tounits a and and it will be clear from the drawing that when relay L isenergized, as when lamp G or Y is energized, current is supplied tosection A.B by winding 14. Due to unit 6, however, current can flow inone direction only through this circuit and rail 1 is therefore positivewith respect to rail 1 Under these conditions, current of what I shallterm normal relative polarity is supplied to section AB. Similarly, whenrelay F is energized, as when lamp R is lighted, current is supplied tosection AB by winding 15, but under this condition rail 1 is positivewith respect to rail 1. Under these conditions current of what I shallterm reverse relative polarity is supplied to section AB.

As shown in the drawing, a train, indicated diagrammatically at V,occupies the section to the left of A. Current is therefore shunted awayfrom the relays J and K and relays J K and L are de-e-nergized. As aresult, relay H is ole-energized, so that lamp R is lighted and relay Fis energized. A stop indication is therefore displayed at point A, andtrack circuit current of reverse relative polarity is supplied tosection AB by winding of transformer T Relay K is therefore energizedand relay L is also energized, but relay J is cle energized. As aresult, lamp Y is energized and a caution indication is displayed atpoint B. The energizationof relay K also energizes relay H so that lampB is de-energized but relay F is tie-energized. Track circuit current ofnormal relative polarity is therefore supplied to section B-C fromwinding 14 of transformer T This track circuit current flows throughheaters 8 of relays L and J C and energizes these re lays but relay K isde-energized. Lamp G is therefore energized and relay H is alsoenergized. It follows that lamp B" and relay F are both de-ene-rgized.Aproceed indication is therefore displayed at point C and track circuitcurrent of normal relative polarity is supplied to the track section tothe right of point C by winding 14 of transformer T Referring now toFig. 2, the apparatus is similar to that described for Fig. 1 exceptthat the thermo-sensitive relays J, K, F and H are constructed so thatthe heater f each relay is in electrical contact with thethermo-sensitive element 9 of such relay. TVhen the heater is energizedtherefore the current can flow through the thermo-sensitive element tothe heater of the relay.

The heater 8 of thermo-sensitive relays J and K for each section areconnected in parallel across the rails adjacent the entrance end of thecorresponding section through the asymmetrical units 4 and 5 as in Fig.1, but the common terminal cl of these heaters is connected directlywith the rail 1 instead of through the heater 8 of a relay L as in thepreceding figure. Referring particularly to the apparatus located atpoint A, the circuit for lamp G may be traced from secondary 11 oftransformer T through wire 36, lamp G wire 43, thermo-sensitive element9 and heater 8 of relay J wires 39, 10 and a1, heater 8 of relay H wire42, and resistance 2 1 back to secondary 11 of transformer T Thiscircuit is closed only when relay J is energized. When relay K isenergized current flows from secondary 11 of transformer T through wires36' and 37, lamp Y wire 38 thermo-sensitive element 9 and iio lili) emma7 heater =8 of relay K wires 39, 40 and '41,

heaterB of relay H wire 42, and resistance is energized.

ondary "of transformer T through wire 41%, lamp B, heater 8 of relay Fwire a6, a portion of resistance 2st, and wire 6.0 "hack to secondary 12of transformer The parts are "so. proportioned when current is beingsupplied to either of the lamps G? or 'Y+*:the potential drop across theportion of resistance '24 which is included in the circuit for lamp Bt-is .equal in magnitude and 0p posits in direction to'etheelectromotiveforce supplied by secondary 12 of transformer'T When either of lamps G0.1: Y is lighted, then,:no current flows the circuit for lamp R andthis lamp and relay F are then both dc-energized; When relays J and'Kare both cl'e energized, however, so that no cur rentflows fromsecondary ll through resistance 24:, the electromotive force supplied bysecondary .lQfof transformer T supplies a current to the circuit of lampR which energizes thislanrp and the heater 8 of relay F T re left-handterminal secondary 1-5 of transformer .T is constantly connected withthe right-hand terminal of secondary lla-nd is also connected by meansof wire 51 with rail 1 of section AB; The right-hand terminal ofsecondary 15 is connected through wire 48, asymmetrical'unit 7, wire 49,thermo-sensitive element 9 of heater 8 of relay H and wires ll, 40 and50 to the rail 1 of section A-B. It follows that when relay H isenergized, current of normal relative polarity is'supplied to the railsof section AB. The left hand terminal of secondary 'llis connectedthrough wire '54, asymmetrical unit =6, wire 53, thermo-sensitiveelement 9 and heater 8 of relay F and Wires 52, 40 and '50 to rail 1 ofsection AB. When relay F is energized therefore,current of reverserelative polarity is supplied to the rails of section A B from secondary14L.

As shown in the drawing the section to the left of point A is occupiedby a train V. Current is'therefore shunted awa from the heaters 8 ofrelays J and K and these'relays are (lo-energized so that no current canLamp R flow through lamps G or Y is therefore energized to give a stopindication and relay F is also energized but relayH is de-energized.Current of reverse relative polarity is therefore supplied to the "railsof section AB from secondary 14 of transformer T. This currentilowsthrough asymmetrical unit 5 to heaterv 8 of relay K but cannot flowthrough asymmetrical unit The circuit for lamp R passes from secv 4 toheater '8 of relay J Relay J is therefore de-ener'gized, and relay K isenergized so that current flows from secondary 11 of transformer Tthrough lamp Y' thereby giving :a caution indication. Relay H istherefore energized, but the current flowing through resistance-2415mmsecondary llneutralizes the electromotive force supplied by secondary112 of transformer T sothatlamp R is extinguished and relay F isde-en'en gized. Current of normal relative polarity is thereforesupplied to the rails of section B' O from secondary 15 of "transformerT This current energizes relay J but relay .K is de-energized. Currenttherefore flows from secondary .11 of transformer. T through lamp G9,lighting thislam'p to give a proceed indication. Relay H is energizedand relay. F is de-energized and lamp R isextinguished. Current ofnormalrelative polarity is th'erefore supplied to the rails of the section-tothe right of point C by secondary of transformer T One advantage of theapparatus shown Fig. 2 over th-atshown in Figure l isth'at in Fig. 2only one thermo-sensitive relay is energized at a time at the entranceend of each track section and the power required to operate theapparatus is therefore less thanin Fig. 1, where two thermo-sensitiverelays are always energized at this point.

Other advantages are the savings resulting from the elimination of onethertmo-sensitive relay and one winding of transformer T for each signallocation.

Although .I have herein shown and described only two forms andarrangements of railway signaling. apparatus embodying my invention, itis understood that various changes and modifications may be made thereinwithin the scope of the appended claims without departing from thespirit and scope of my invention.

I claim is:

1. In combination, a forward and a rear track section, thermo-sensitiverelays associated with said forward section, means controlled by saidthermo sensitive relays for supplyingsaid rear section with trackcircuitjcurrent of one relative polarity or the other depending ontralhc conditions in said Having thus described my invention whatforward section, traffic governing means for 3,111- coinbinat-ion, astretch of railway track, means for at times supplying said stretch withtrack circuit current or one relative polarity or the other,thermo-sensitive sensitive relay and an asymmetrical unit for said rearsection responsive to such current, and tratfic governing means for saidrear section controlled by said relay and byv said unit. 7

5. In combination, a stretch of railway track, means responsive tot'aiiic conditions in advance for supplying said stretch with trackcircuit current of one relative polarity or the other, a thermosensitiverelay connected with said stretch, an asymmetrical unit interposedbetween said stretch and said relay, andtraiiic governingmeans controlled by said relay.

6. In combination, a stretrhoi": railway track, two sources of energy,two tn'ermosensitive relays one for connecting each said source with therailso'f the stretch when the associated relay is energized, means forenergizing one said relay or the other in accordance with trafficconditions, an asymmetrical unit interposed between said stretch and onesaid source, a second oppositely disposed asymmetrical unit' interposedbetween said'stretch and the other said source, and trafiic governingmeans responsive to the relative polarity of the current in saidstretch. a y

7. In combination, a stretch of railway track, two thermo-sensitiverelays each having a heater, means for connecting one terminal of eachheater to one rail of said stretch and for connecting the other terminalof each heater to the other rail, an asymmetrical unit interposedbetween one heater and one rail of said stretch, an'oppositely disposedasymmetrical unit interposed between the remaining heater and one railof the stretch, and traiiic governing means con trolled by saidthermo-sensitive relays.

8. In combination, a stretch of railway track, means for supplying saidstretch with track circuit current of one relative polarity or the otherin accordance with traiiic conditions, 2. thermo-sensitive relay, meansincluding an asymmetrical unit for connecting said thermo-sensitiverelay with said stretch, and trafiic governing means controlled by saidrelay.

9. In combination, a stretch of railway,

* track, two thermo-sensitive relays, an asymand means controlled bysaid relays andby said asymmetrical units for supplying-said stretchwith track circuit current of one relatively polarity or the other inaccordance with trailic conditions. v v

10. In combination, a stretch of railway track, two thermo-sensitiverelays,.an asymmetrical unit associated with each said relay, meanscontrolled by said relays and by said asymmetrical units for supplyingsaid stretch With track circuit current of. ione relative polarity orthe otherin accordance with traiiic conditions, and traffic governingmeans responsive to the polarity of such current. V 1

11. In combination, a stretchof railway track, two thermosensitiverelays, an asymmetrical unit associated with each suchrelay, andmeanscontrolledby said relays and by said asymmetrical units for supplyingsaid stretch with track circuit current of one relative polarity or theother in accordance with traliic conditions; v 12. In combination, astretch'of railway track, means for supplying said stretch with trackcircuit current of one relative polarity or the other in accordance withtrat'fic'conditions, a thermo-sensitive relay, means includin anasymmetrical unit for connecting said thermo-sensitive relay with saidstretch, an. indicator controlled by said thermo-sensitive relay, and asecond indicator arranged to be tie-energized when said first indicatoris energized.

.13. In combination, a stretch of railway track, means for supplyingsaid stretchwith track circuit current of one relative polarity or theother in accordance with tra fiicconditions, a trackway signalcomprising a plurality of indicators, a thermo-sensitive relay forcontrolling one said indicator, means including an'asymmetrical unit forcon necting said relay with said stretch, a second thermo-sensitiverelay for controlling the second said indicator, and means including anasymmetrical unit oppositely disposed with respect to said first unitfor connecting said second thermo-sensitive relay withlthe stretch.

ltpIn combination, a stretch of railway track, means for supplying saidstretch with track circuit current of one relative polar- I ity or theother in accordance with traffic conditions, a trackway signalcomprising a plurality of indicators, a thermo-sensitive relay forcontrolling one said indicator, means including an asymmetrical unit forconnecting said Yrelay with said stretch, a second thermo-sensitiverelay for controlling the second said indicator and means including anasymmetrical unit oppositely disposed with respect to said first .unitfor connecting said second thermo-sensitive relay with the stretch, anda third indicametrical unit associated with each said relay,

tor arranged tov be de-energized when either said first or said secondindicator is ens-r gi-zed Y 1-5. In combination, a stretch of railwaytrack, a trackway signal responsive to trafficconditions, niea-nsincluding a thermosensitiv-e relay and an asymmetrical unit forsupplying track circuit current of one characteristic to said stretchwhen said nal is displaying one indication but not when said signal isdisplaying a different indication, and traffic governing meansrcsponsiveto said current.

1 6. In combination, a s retch'of railway track, a traclrway signalresponsive to traffie conditions, and means therm'o-sensitive relay andan asymmetricalunit for supplying track circuitcurrentof one relativepolarity to said; stretch when the signalis displaying one indicationand for supplying traek ci'reni-t current of the other relative polarityto the stretch when the signal is displaying a different indica tion.

17. In combination, a stretch of railway track, means for supplying saidstretch with track circuit current of one relative polarit-y or theother in accordance with trafic condition, two thermo-sensitive relayseach comprising a heater, means for connecting said heaters in parallelacross the rails of said stretch, two asymmetrical units one interposedbetween each heater and one rail of the stretch, and traficgoverningmeans controlled by said thermo-sensit-ive relays.

18. In combination, a stretch of railway track, means for supplying saidstretch with track circuit current of one relative polarity or the otherin accordance with trafiic conditions, two thermo-sensitive relays eachcomprising a heater, means for permitting current from said stretch toflow only in one direction through one heater and only in the otherdirection through the remaining heater, and traffic governingmeanscontrolled by said thermo-sensitive relays.

19. In combination, a stretch of railway.

track, means for supplying said stretch with track circuit current ofone relative polarity or the other in accordance with traflicconditions, two thermo-sensitive relays each comprising a heater, meansfor connecting said heaters in parallel across the rails of saidstretch, two asymmetrical units one interposed between each heater andone rail of the stretch, and two indicators one controlled by each saidthermo-sensitive relays.

20. In combination, a stretch of railway track, means for supplying saidstretch with track circuit current of one relative polarity or the otherin accordance with traffic conditions, two thermo-sensitive relays eachcomprlsing a heater, means .for connecting said heaters n parallelacross the ralls of said including a stretch, twoasymmetrical units oneinterposed between each heater and one rail of third indicator arrangedto be de-energized wl'ien'either; of said first two indicators is encrgi/ied. i l

- 21. In combination, a stretch of railway rack, means for supplyingsaid stretch with track circuit current of" one relative polarity or tlother in accordance with traffic con dit-ions, two thermo-sensitiverelays each comprisinga heater; means for connecting said heaters. inparallel across the rails of said, stretch, two asymmetrical units onein terposed between each heater and one rail of the stretch,twoindicators one controlled by each said thermo-Ccnsitive relay, :1third thGIliIO-SGDSLIVB' felily controlled by said first two:thermo-sensitive relays, and a third indicator controlled by said thirdithermosensitive relay.

22. In combination, a stretch of railway track comprising a forward anda rear section, mean-a for supplying said forward section with trackcircuit current of one relative polarity or the. other in accordancewith traflic conditions, a first and a second thermosensitive relay eachcomprising a heater,

connected across the rails of said forward section, two asymmetricalunits oppositely connected in series with said heaters respectively, athird and a fourth thermo-sensirive-relay; a circuit for the heater ofsaid third relay including a source of energy,a resistance, and thethermo-sensitive elements of said first and second relays in parallel; acircuit for the heater of said fourth relay including a second source ofenergy and a portion of said resistance; and means for supplying therails of said rear section with current of one relative polarity or theother according as said third relay or said fourth relay is energized.

23. In combination, a stretch of. railway track comprising a forward anda rear section, means for supplying said forward section with trackcircuit current of one relative polarity or the other in accordance withtrafiic conditions,'a first and a second thermosensitive relay eachcomprising a heater connected across the rails; of said forward section,two asymmetrical units oppositely connected in series with said heater-srespecincludinga second source of energy and a portion of saidresistance; a third source of energy, means for supplying current of onerelative polarity to the rails of said rear section from said thirdsource when said third relay is energized, a fourth source of energy andmeans for supplying current of the opposite relative polarity to therails of such rear section when said fourth relay is energized. p I

12%. In combination, a stretch of railway track comprising a forward anda rear section, means for supplying said forward sec tion with trackcircuit current of one relative polarity or the other in accordance withtrafiic conditions, a first and a second thermosensitive relay eachcomprising a heater connected across the rails of said forward section,two asymmetrical unit-s oppositely connect-ed in series with saidheaters respectively,a third and a fourth thermo-sensitive relay atransformer comprising a primary constantly supplied with alternatingcurrent and four secondaries; a circuit for the heater of said thirdrelay including one of said secondaries, a resistance and thethermosensitive elements of said. first and second relays in parallel; acircuit for the heater'of said fourth relay including a secondsecondaryof said transformer, and a portion ofsaid resistance, means forconnecting the common terminal o'fthe third and fourth transformersecondaries with one rail of said rear section, means includin anasymmetrical unit and the thermo-sensitive element of said third relayfor connecting the free terminal of said third secondary with the otherrail of the rear section, and means including a second oppositelydisposed asyme metrical unit and the thermo-sensitive ele-- ment of thefourth relay for connecting the free terminal of'the fourthtransformersecondary with such other rail of said rear section. V

In testimony whereof I afiix my signature,

LABS o. GRONDAHL.

